DIY staghorn rock?

[Delphinus]

Trying to figure out a way to make some DIY rock in the shape of staghorns (thin branchy rock, almost like "deer antler" shapes maybe).

Would it be better to make a mould maybe?

The one thing I could think of (other than a mould), but it wouldn't work so great for a reef tank: take some copper household wire, twist a few together and then flick aragocrete onto it until you have a "rock." The only problem is the copper wire! but I can't think of anything else to use as a "skeleton" that would work as well. Need something relatively inexpensive/disposable, shape-able, and inert ... but can't think of anything that fits the bill.

Any ideas? Love to hear 'em!!